With the advent of the speech synthesizer, toys having a speaking function have appeared on the market. These toys are normally actuated by switches, such as push buttons, on a one-to-one basis, that is, each switch actuates a single letter or symbol. Thus toys have been proposed which incorporate a full size keyboard for providing instructions for a speech output. Such keyboards require two handed operation and are extremely expensive. They are clearly not applicable to portable toys.
Chordic keyboards are known in the patent literature. Examples of such keyboards are described in U.K. Patent Specification No. 1,496,522 and in published U.K Patent Application Nos. 2,015,220 and 8,036,839.